Technical Field
The disclosure in generally relates to a high density memory device and method for fabricating the same, and more particularly to a three dimensional (3D) memory device a method for fabricating the same.
Description of the Related Art
Non-volatile memory (NVM) devices which are able to continually store information even when the supply of electricity is removed from the device containing the NVM cells has been widespread adopted by bulk solid state memory applications in portable audiovisual entertainment devices, cell phones or digital cameras etc. Recently, various 3D memory devices, such as a 3D single gate vertical-channel (SGVC) flash memory device that has a multi-layer stack structure may possess a higher density memory and excellent electrical characteristics, e.g. reliability in data storage and high operating speed, has been provided in order to accommodate the rising demand for superior memory.
A typical method for fabricating a 3D SGVC flash memory device includes steps as follows: A plurality of word line trenches are formed in a multi-layer stack, and a memory layer with an ONO composite layer (including a silicon oxide layer, a silicon nitride layer and another silicon oxide layer) and a poly silicon channel layer are formed in sequence on the bottoms and sidewalls of the word line trenches, so as to define a plurality memory cells connected in series and disposed on the vertical sidewalls of the word line trenches.
However, as semiconductor features shrink in size and pitch, the problems of degradation in electrical properties and memory write/read failure due to corner effect occurring at two lateral edges of each memory cell is getting worse.
Therefore, there is a need of providing an improved 3D memory device and the method for fabricating the same to obviate the drawbacks encountered from the prior art.